


Sibling Rivalry

by eprime



Category: Harry Potter - J. K. Rowling
Genre: M/M, Threesome, r/s anon kink meme
Language: English
Status: Completed
Published: 2011-02-09
Updated: 2011-02-09
Packaged: 2017-10-15 13:31:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,417
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/161274
Author URL: https://archiveofourown.org/users/eprime/pseuds/eprime
Summary: <blockquote class="userstuff">
              <p>Just how far is Sirius willing to go to bring his brother over to the right side?</p>
            </blockquote>





	Sibling Rivalry

**Author's Note:**

> Written for the [RS Anon Kink Meme](http://ceredwensirius.livejournal.com/206827.html). Prompt: Sirius/Remus/Regulus: The Black brothers have never been very good at sharing.

When Sirius had enlisted Remus' help in trying to salvage his relationship with Regulus he hadn't expected it to come to this.

"You heard me quite clearly."

Regulus sat primly in one of the two armchairs by the fire in his Prefect's Study, hands folded in his lap and ankles crossed below. Remus sat in the other chair. He was staring blankly into the flames, seemingly oblivious to Regulus' outrageous proposal.

All Sirius could do was sputter for several seconds until he was able to formulate a coherent and appropriately vehement response.

"Have you gone completely off your nut? Remus is _mine_!"

Remus cleared his throat, finally looking up at Sirius with an arched brow and hint of amusement.

"You _are_ ," Sirius growled. "Don't even try to deny it, Lupin."

He rounded on his brother when Regulus sniggered.

"You!" He stabbed a finger toward him. "How could you even expect--"

"You asked me what you could do to convince me that you've got the right of it. I've told you." Regulus lifted his shoulders in an elegant shrug.

"Right. And shagging _Remus_ will make you turn your back on all the Pureblood fanatics you've been cosying up to all these years?"

Regulus opened his mouth, but before he could speak he was interrupted by the sound of Remus chuckling. Sirius turned to him, incredulous.

"It's not _funny_ , Remus."

Smiling, Remus just shook his head. "Can't you see he's just having a laugh?"

Sirius frowned, casting a doubtful look at his brother.

"I assure you, I'm not joking."

"See!" Sirius glared at both of them.

His smile fading a little, Remus stared down at the floor. "Regulus, if you've no interest in really listening to us then just say so. I'm sure it's amusing to toy with your brother, but regardless of what you think, he _is_ concerned about you."

"But I'm not toying with him. Not that I can deny his reactions give me _some_ satisfaction, but I mean what I say." Regulus placed his hands on the armrests of his chair, regarding Remus intently.

Remus frowned.

"Is it so hard to believe?"

"Yes."

The answer came out clipped, and Sirius moved to sit on the arm of Remus' chair, one hand settling on Remus' shoulder.

"Why?"

Remus raised his eyes. Years of experience told Sirius that underneath his calm exterior he was anxious and perhaps a little angry.

"Have you forgotten I'm a half-blood?"

"What better way to teach me how wrong I am to harbor blood prejudices?"

Sirius snorted, but Remus' eyes flashed.

"So Regulus Black, last hope to carry on the illustrious main branch of the Black Family line, is a shirtlifter, then?"

A thin smile turned up Regulus' lips, but Sirius threw back his head laughed.

"As you say."

Remus stood abruptly. "I'm sorry, Sirius, but I'm going back to the dorm. It's obvious that Regulus is--"

"Wait." Regulus stood, too, waiting until Remus met his eyes. "Hear me out."

Sirius was torn between wanting to drag Remus out himself and listening to how his brother tried to spin his line of rubbish. He came up next to Remus, resting a hand on the small of his back in a small display of possessiveness. A high spot of color bloomed across Regulus' cheekbones. Remus stood there, expression impassive, but he didn't leave.

"We've always gotten along well enough, I thought," Regulus began carefully. "Haven't we?"

Grudgingly, Remus nodded. "Given the circumstances."

"Exactly. Given the circumstances it was difficult to...expect more."

"What's your point, Regulus?" Brow furrowed, Remus studied Regulus' guileless expression. It was the same look of innocence that Sirius had seen him use when they were children and flat out lying to their mother, so it didn't offer Sirius much comfort here.

"The point is, you've always intrigued me. At first, it was because my brother was so taken with you, even when we were younger, and then I got to know you a bit more through him and then through Prefect duties. I watched you over the years, as well."

That startled Remus. His mouth fell open and his lips worked a moment. Sirius felt his body tense slightly beneath his fingertips in what he knew was apprehension. "You watched me?"

Regulus inclined his head. "You can ask Sirius. We've always had similar tastes in many things."

His startled eyes met Sirius' for a moment, and Sirius didn't know how to react. It _was_ true enough, but he could hardly bring himself to believe this. He didn't want to believe it. Without consciously thinking of it, he drew Remus closer to him, resting his hand on his hip.

Regulus smiled knowingly. "Sirius knows it's true. I fancy you--just like he does. I want..." He paused considering his words carefully before speaking them in his precise, cultured diction. "I want more than just to have you once. It isn't a game. I want the same chance you've given my brother. I want you in my bed. I want to kiss and touch and fuck you."

Both Remus and Sirius sucked in a shocked breath.

Eventually, Remus broke the silence. "Why are you only saying something now?"

A wry smile flitted across Regulus' face. "Because I didn't have anything you wanted until now. And you'll be gone next year. This is my only chance."

This was too much for Sirius. "I want to you be my brother. I want to get you away from the crowd you run with and our parents and all that rubbish that is going to end up with you dead or worse! I don't want you fucking my boyfriend, for fuck's sake! You think I'm just going to hand him over to you on a silver plate?"

His face settling into a composed mask again, Regulus looked at him. "I'm willing to share."

Remus flushed deep red as a sound of incredulous disbelief came from Sirius.

"This is..." Remus' voice faltered for a moment. "I can hardly believe we're having this conversation, but it doesn't matter anyway."

Both Blacks looked at him. "I love Sirius, and I won't do anything that would hurt him." At this, Sirius squeezed Remus' hip reflexively. "And...Regulus...you don't know...you wouldn't--"

"I know," Regulus cut in. "I know what you are."

Remus went white, suddenly resting heavily against Sirius' side. Sirius held him firmly, supporting him, all while staring at Regulus with shock and the beginnings of a protective anger.

"What?" Remus whispered

"I know what you are." Regulus regarded him steadily. "I know where you go every month. You're a w--"

"Shut it!" Sirius spit out. "Who told you? It was Snivellus, wasn't it? I'll fucking rip his bollocks off."

"It wasn't Snape. Though, what happened between you last year helped me figure it out."

Remus sagged further, staggering back to fall into the chair he'd been sitting in before.

"Remus." Sirius was kneeling at his side in an instant, reaching a reassuring hand to rest on his leg.

"Is this some sort of blackmail, then?" Remus didn't look up. His voice was low and measured, though Sirius could see the faint trembling in his hands.

For the first time, Regulus looked uncertain, even vulnerable. "No. That's not...not what I meant. I won't tell anyone whatever happens. I _haven't_ told anyone."

Sirius shot him a filthy glare. "We're supposed to believe you? Not to mention believing that after years of toeing the line you're keen to have it off with a half-blood werewolf?"

Remus stiffened, and Sirius was slammed with the realization of what his words sounded like. Horrified, he looked up at Remus. "No--Remus, I'm so sorry. I didn't mean it like that. I was just--"

"I know." Fingers wrinkling the clean press of his slacks, Remus shook his head to deny the apology. "I know you didn't. But it's true, isn't it? Why would you want me?" He looked at Regulus.

"I don't know." Almost unwillingly it seemed, Regulus took a step forward, eyes locked on Remus. "I don't _know_." He sounded angry. Frustrated. "I didn't _want_ this. I fought it. But I can't help myself."

He shot Sirius a look that was a mix of accusation and anger when Sirius scoffed.

"You left _me_. So don't talk to me about the company I've been keeping, brother."

A flush of guilt shaded Sirius' features, but he clenched his jaw furiously. "You could've come with me."

"No, I _couldn't_. Your way isn't mine, Sirius. It never will be."

"Then what's this all about, then? Just a pack of lies? Do you have any idea what you're really dealing with? I thought you said you'd give up the thought of ingratiating yourself with that lot."

"Do _I_ have any idea. Sirius, you utter fool, I know better than you what's in store. You're so blindly arrogant. You always have been."

"Fuck you."

Regulus laughed. "Do you want to? Are you jealous that I want Lupin?"

Sirius launched to his feet, but Remus was there, pulling him back and getting between them.

"What exactly are you saying, Regulus? If we were to agree to this--"

"Remus!"

"Wait, Sirius." Remus pushed harder on Sirius' chest as he began to protest, speaking over him. "If we were to agree, would you be able to... _willing_ to leave all that?"

"No."

Sirius gave a vicious nod, as if it was what he expected, while Remus just look perplexed.

"I can't leave Mother and Father. They're not well, and I _won't_ , Sirius. Don't look at me that way. And anyway, it's better if I maintain my contacts here and outside of school. I can help you better that way."

"Help us?" Remus' eyes pierced him. "Help us how?"

"I know Dumbledore has talked to you."

Sirius and Remus paled.

"It's no secret to certain people he's running his own game and recruiting to his side. I can tell you things. I can--"

"Spy?" Sirius laughed derisively. "You're a Sixth Year, Reg. I doubt Dumbledore would recruit _you_ , even if there was anything to your crazy idea."

"Don't treat me as if I'm stupid, Sirius. And don't try to bluff me. I know you, and I'll wager Dumbledore would be quite eager to hear what I have to say. But we don't have to involve him about this. Not now. I don't know much of anything of value yet, anyway, but I will. And next year, when you're out there, away from school, you just might be glad of my help."

"It's too dangerous, Regulus." As Remus let his hand drop from Sirius' chest, Sirius went cold. It _was_ a crazy, dangerous idea. He didn't want his brother in danger no matter how angry he made him. And the fact that Remus was taking this whole farce seriously was even more disturbing.

"That's my look out."

"The whole point was to get you away from them."

"I thought the point was to make sure I didn't become a Death Eater." Sirius and Remus flinched at the name. "And I won't. Not _really_."

"Can't you just--" Remus tried.

"I've told you want I want." Regulus' eyes widened in the same beseeching way that Sirius' did when he really wanted something, when he wasn't willing to take no for answer. "I just...I want this...I need it--something for _me_. Please." His plea made his eyes, so like Sirius' own, go darker. His veneer of untouchable reserve was gone, and he seemed younger and more vulnerable than his seventeen years. "Just until the end of the year. It's only a few months. Just that...give me that much time."

Remus reached back, fumbling for Sirius' hand and tangling their fingers together tightly. Sirius wasn't sure if it was pity or deep empathy that kept him silent and acquiescent when Remus spoke next.

"We'll think about it."

* * *

 

In the end, they took Regulus to the Shack. Neither dorm was remotely feasible, and getting caught _in flagrante delicto_ in some abandoned classroom was simply unthinkable. The wizarding world took a lax view toward extremely close family relations, it was true, but they were all fairly certain that the two Black brothers and a half-blood Prefect caught out in a torrid threesome would cause a scandal that would shake Hogwarts to its foundation. For Sirius had insisted on being present. That was part of the bargain. Not that he _wanted_ to have a go with Regulus, but he wasn't about to let him have Remus all to himself.

It had taken days for Remus and Sirius to settle into the idea, no matter that after the arguments and insecurities and constant reassurances they had finally, with deep reservations and even deeper desperate hope, come to terms. But it wasn't until Remus had curled up against Sirius one evening, whispering in his ear that it would be like having two of him, what with Regulus looking so much like him. _Two of you fucking me, Sirius. Just think of it._

Sirius had, and though the idea was titillating, it couldn't completely choke off the burning possessiveness and jealousy he felt at the thought of his brother touching Remus in intimate ways. _He's not me, though_ , he had said petulantly.

 _Of course not, he's not nearly as good looking as you,_ Remus had assured him. _Though he has much better manners._ Sirius had playfully wrestled Remus down and proceeded to show him _all_ the ways he was superior to his younger brother.

But now that they were here, Sirius was leaning against the wall, arms crossed as Regulus paced around the room, taking in the newly transfigured contents which consisted mainly of a ridiculously large bed covered in scarlet sheets and pillows and not much else.

After he'd made a circuit of the room, Regulus lifted one delicate eyebrow. "I see that my brother was in charge of decor."

Remus laughed, settling awkwardly on the edge of the bed. "Up Gryffindor bordello style doesn't suit you?"

"I suppose it is rather appropriate under the circumstances." Regulus gave a small smile, though he crossed his arms, hands disappearing into the sleeves of his robes, a habit Sirius knew indicated his brother was trying not to show his nervousness.

"Don't like it, you can leave," Sirius offered with a narrow-eyed look. He came to stand in front of Remus, extending a hand and pulling him to his feet, though his eyes stayed locked on Regulus.

"I'm not leaving."

"Suit yourself." With a dismissive shrug, Sirius turned to Remus and pulled him into a possessive kiss, relishing the sound of Regulus' sudden intake of breath.

Remus moaned as Sirius sucked his tongue hard, causing Remus to stumble forward against his chest. Sirius slid his hands behind Remus, gliding them down over the curve of his arse and pressing their hips together so that Remus could feel his hardening cock. "I'm going to fuck you, Remus," Sirius promised, moving his lips to Remus' ear. "Better than my brother or anyone else ever could."

"Don't be so sure."

Always light on his feet, Regulus had moved before Sirius had known it, insinuating himself behind Remus and touching him with a confidence that rather shocked Remus and Sirius both. His hands slid over Remus' chest, and Regulus pulled him back, away from Sirius, fingers slipping beneath the fabric between the buttons of Remus' white shirt to caress the skin there.

When he licked behind Remus' ear, catching his teeth on his earlobe and scraping across the soft flesh, Remus shivered. His eyes flew up to meet Sirius'. They both looked as they felt--caught off guard with an almost unwilling mix of arousal, apprehension, and in Sirius' case, seething jealousy.

A slow, challenging smile curved Regulus' mouth as he caught Sirius' gaze, his teeth still fastened on Remus' ear. Sirius narrowed his eyes again, sliding his wand out in a subtle motion and casting a wordless spell. Every article of clothing Remus was wearing vanished, and he flushed in heated embarrassment, crying out Sirius' name with a scandalized gasp that made Sirius smile wickedly.

In an instant, he was on knees, lips wrapped around Remus' prick, tongue working the head just the way he knew Remus loved it. Remus' head rolled back against Regulus' shoulder, his hands coming up to clench in Sirius' hair.

 _Take that, Regulus_ ," Sirius thought with vindictive pleasure. His victory was short-lived, for Regulus had cast his robes aside and knelt on the floor behind Remus, and the next thing Sirius knew Remus gave a sharp cry, his hips bucking forward, almost making Sirius choke.

" _Oh, God_." The words came out breathy and higher pitched than Remus' normal tone, and his hips jerked again as Regulus repeated whatever it was to make Remus react like that. Sirius had a sneaking suspicion he knew just what Regulus was doing back there.

With greater determination, Sirius redoubled his own efforts, sucking Remus down to the root and grazing lightly back up with his teeth in a way he knew drove Remus wild. He had to grab his hips and hold him hard to keep from thrashing about as he and Regulus both worked Remus with their tongues, Regulus fucking his hole and Sirius licking his leaking slit. Remus tossed back his head and moaned like he was dying, tugging painfully at Sirius' hair as Sirius sucked him deep again and swallowed around his thick shaft.

Regulus, the little tosser, must have stuck his finger up inside Remus, too, because his hips shot forward again in a helpless thrust, and Remus gave a wild cry shooting his load down Sirius' throat, his fingers untangling from Sirius' hair once the tremors from his orgasm had faded enough that he could support himself unaided on his trembling legs.

He stumbled to the edge of the bed and collapsed against it, staring at the two brothers with rather dumbfounded amazement.

"Ready for my cock, Moony?" Sirius asked him with a cheeky grin. He stood and began stripping off in front of him.

"Not so fast." Regulus rose, too. "Seeing as how it was _my_ tongue and fingers inside him, getting him all wet and opened up, I believe I should have first claim."

That shook Remus out of his daze, and he blushed darkly.

"Like hell," Sirius snarled. Nobody should make Remus blush like that but him, and Remus was _his_ to claim, no one else's.

"Sirius--"

"Shut it, Remus!" This was all his fault anyway.

"I knew you'd back out," Regulus sneered. "So much for Gryffindors and their honor. You never did like to share."

Sirius scowled, snatching his wand from the pocket of his discarded robe, while Regulus drew his own wand. "You always wanted what was mine. Find your own fucking toys."

"Oi!" Remus sat up straighter, looking highly indignant. "I'm not a--"

"Stay out of it, Remus! This is between my brother and me." Sirius lifted his wand. "He obviously needs a reminder about touching my things."

Regulus took up a dueling stance and smiled grimly. "I'm not the same little boy you remember, brother. Don't underestimate me."

"Oh, for--" Remus huffed, standing to move between them. "Stop this, Sirius. You agreed. Can't we--"

Remus was scolding _him_? A hot haze made Sirius' mind fog, and without thinking he cast a _Silencio_ at Remus, and when Remus' shock gave way to an angry look as he made a snatch for Sirius' own wand, Sirius cast another spell that sent Remus flying onto the bed and then another to bind his wrists together above his head.

The sight of Remus writhing furiously against the sheets brought Sirius back to more immediate concerns. The first being that Remus was going to kill him later. The second, and more important one, was that his own cock was diamond hard and still trapped in his pants. He turned to see Regulus looking remarkably discomposed, his mouth even slightly open as he stared at Remus bound and naked on the bed. Sirius felt something like pride at the effect his Remus was having on his brother. It loosened something in shoulders, and made most of his anger recede in a wave of something he wasn't quite sure he wanted to define.

Making a sudden decision he finished shedding his remaining clothes, letting his cock spring free. He shot Regulus an unreadable glance as he did the same. Wetting his lips, Regulus took a step closer to the bed, and then he looked at his brother.

"Please, Sirius. You can go first. You can fuck him open for me, get him hard again and begging for it. And then...and then I'll take over. I'll fuck him for you so good." Regulus' eyes were wide open and soulful, manipulating Sirius in a way that had always worked when they were kids. It seemed so _wrong_ that it was working now, that there was something disturbingly erotic about it. "You'd like to see that wouldn't you? You can show me...teach me how to fuck him just how he likes. I'll do whatever you say."

 _Fuck_. Sirius had to swallow to stifle a groan, his cock was standing out from his body, flushed and aching already. He could tell Regulus to get out. It would be done and he could climb on the bed, push Remus' legs up and fuck him raw. _Almost_ unwillingly, his eyes flickered down to his brother's body to see that he was in the same state. Their eyes met again, and Sirius nodded sharply. "Get on the bed."

Regulus slid next to Remus with a grace that belied his obvious eagerness, and Sirius crawled up between Remus' legs, unable to resist the urge to smirk as Remus' expression flickered between open lust and anger. He jerked his wrists, fighting the rope until Sirius pushed his legs up to his knees and slid two fingers inside him without preamble.

Though Remus was still voiceless, Sirius didn't miss the gasp as he scissored his fingers inside him. Regulus _had_ done an excellent job of loosening him up, and Sirius didn't bother much longer with preparing him.

"Let him suck you." Sirius pressed the head of his cock against Remus' hole. "He's fucking amazing at that."

Regulus' eyes went dark and he wasted no time straddling Remus, shifting up his body until he could brush his cock against Remus' lips. Sirius could tell that Remus had opened his mouth to allow him entrance when Regulus shuddered in front of him. At that moment, Sirius shoved inside Remus, gripping his thighs tightly as he hilted himself in one hard push.

Regulus cried out, and Sirius allowed himself a thin smile. "That's good, Remus," he purred. "Take it, show him how much you love having a thick, hard cock in your mouth...down your throat."

His own reward came quickly as Remus clenched tightly around his cock. Sirius set a slow, but intense pace, each thrust slamming deep without respite. He waited until Remus was fully hard again, watching his cock slapping lightly against his belly as Sirius pumped into him, before withdrawing with an obscene sound as his cock pulled out of him. Remus' hole flexed like a greedy mouth.

"Fuck, Regulus. Get down here. He's so fucking hot for it now." A quick glance at Remus' face was the only confirmation Sirius needed. He was flushed all the way down his chest, unable to look at him or Regulus as they both knelt between his legs. Regulus reached out to touch a fingertip against the raised pucker, making Remus' hips raise in a wanton little motion.

"Do it, Reg. Fuck him now. I want to watch." Regulus gave a small moan, taking Sirius' place as he shifted aside. Remus was biting his lower lip hard enough to make it go white around the edge of his teeth.

"Start off slow, but make him feel it. He likes it like that. Likes it rough."

Two pairs of grey eyes met, holding, as Regulus slid in, Remus' saliva still slick on his cock. Remus gasped silently, his mouth falling open, and then Regulus was moving faster. Sirius fisted his own cock, taking in every second as Regulus' shaft spread Remus wide, pounding into him to the muttered encouragement of Sirius' own words. "Yeah," he breathed. "Look at him. He fucking loves it. Harder. Fuck him, harder Reg."

Regulus obliged, his hips snapping faster and harder, sweat beginning to bead at his temples and his dark hair falling across his face. Remus looked like a debauched angel, wavy hair spread around his head, expression contorted with lust and pleasure. Sirius couldn't keep his eyes still, he wanted to see everything, the arch of Remus' throat as he tossed back his head, the muscles fluttering in Remus' stomach, the fascinating slide of flesh into flesh as Regulus fucked him into the bed.

Sirius' hand move faster, blindingly fast. "Touch him. Touch him, Regulus." His voice was hoarse and breathless. "Bring him off _now_."

And Regulus reached for Remus' cock which was flushed with blood, veins standing out starkly. He wrapped his hand around it and had barely started to fist it before Remus was spurting over his stomach, wrists jerking ineffectually, wildly, at their magical bonds. Sirius took in everything, the way Remus came undone, Regulus' agonized expression as he, too, went over the edge, coming inside Remus with a hoarse cry.

Only then did Sirius let himself follow, his come shooting over his fist to mark Remus' chest and cock and belly. _Mine_ , he thought hazily, collapsing on the bed next to Remus and burying his teeth in the curve of his throat. Generously, he kept silent when Regulus took up the same position on the other side of Remus, not saying anything when his brother's hand curved over Remus' hip as he curled against him.

The _Silencio_ hadn't worn off yet, but Sirius could see Remus' chest heaving, and he could hear the sound of his brother's and his own heavy breathing. Quietly, he lifted his head. Remus' eyes were closed, and he looked utterly shattered in the best way possible. His gaze moved to Regulus. His brother was staring at him with half-closed eyes, somehow exuding an air of both slyness and vulnerability.

A small, begrudging smile twisted Sirius' mouth and he gave a long-suffering sigh. Regulus always had been a pain in the arse. Manipulative little bugger.


End file.
